[BUG] DM_VIDEO broken on imx6q

Soeren Moch smoch at web.de
Mon Aug 3 17:13:26 CEST 2020


On 03.08.20 15:54, Anatolij Gustschin wrote:
> Hi,
> On Sat, 1 Aug 2020 21:14:10 +0200
> Soeren Moch smoch at web.de wrote:
>> Hi,
>> unfortunately the patch [1] is only the first part to get DM_VIDEO
>> running properly on tbs2910 for u-boot-2020.10. With this, I get a valid
>> video output signal, but no actual video console output, only a blank
>> screen.
>> After some debugging, no with access to a HDMI monitor, the problem
>> seems to be:
>> imx6q has two ipu units, so DM_VIDEO creates 2 video devices. For these
>> two devices also memory for two framebuffers is reserved in
>> video-uclass, starting from gd->video_top downwards. Then vidconsole
>> correctly uses the first video device (ipu1), but apparently the
>> framebuffer from ipu2 at gd->video_bottom. So I see the empty
>> framebuffer from ipu1 while the console output goes to the framebuffer
>> memory of ipu2.
> Thanks for debugging and reporting!
>> I guess there is the same problem on all imx6q devices with 2 ipu units,
>> while on imx6s/6dl devices with a single ipu everything works fine.
>> Disabling the second ipu in the tbs2910 devicetree also helps, but I
>> think this is not a proper solution.
>> What should be done about this? Only probing the first ipu/video device?
> Since the second framebuffer is not in use currently, the probing for
> second ipu device is not done.
>> Assigning the framebuffer memory bottom-up? Using the assigned
>> framebuffer memory of the active video device for console output (seems
>> to be the correct solution, but maybe not so easy to implement)?
> Yes, the later is the correct solution. I've sent a patch.
Thank you very much.
Patch looks good, and really not too complicated. I will try to test
this later today.

Thanks again,
> --
> Anatolij

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